In a conventional liquid crystal display device utilizing a variable transmission polarization axis optical element for rotating the polarization axis of transmitted light of a TN (Twisted Nematic) liquid crystal, an STN (Super-Twisted Nematic) liquid crystal and the like, a structure is employed in which the variable transmission polarization axis optical element is sandwiched by two sheets of polarizers.
According to such an arrangement, only a polarized light component in a specific direction is transmitted through a first polarizer located on the side of a display screen of liquid crystal, and other polarized light components are absorbed by this first polarizer. The polarization direction of the light transmitted through the first polarizer is selectively changed in response to an alignment state of liquid crystal that changes with respect to a voltage applied to the liquid crystal, and the light is incident on a second polarizer located on the other side of the liquid crystal.
In a normally white mode, for example, regarding each of the pixels, (i) in a state where a voltage is not applied to the liquid crystal, light emitted from this liquid crystal is transmitted through the second polarizer, is reflected by a reflecting plate located at the back thereof and thereafter, is transmitted through the second polarizer, the liquid crystal and the first polarizer again to be emitted as display light from the display screen of a liquid crystal display device, (ii) in a state where a voltage is applied to the liquid crystal, the light emitted from this liquid crystal is absorbed by the second polarizer, and the display light is not emitted from the display screen finally.
In this way, light amounts of the display light emitted from the display screen is controlled for each of the pixels using the liquid crystal, polarizers and so forth arranged on the optical path of the external light while reflecting the external light incident from the display screen by a reflecting film provided inside a device, whereby reflective display is effected.
However, since the polarizer, which is an example of a polarized light separator, effects polarization by absorbing polarized light component in the direction different from a specific polarization axis in the incident light, there is a problem in that usage efficiency of light is bad, thus providing dark reflective display.